Spouted bed apparatus with annular region for electroplating small objects

ABSTRACT

A vessel for contacting a plurality of objects with a fluid. An upwardly directed stream of fluid and a portion of the objects are confined in a conduit such that the fluid stream causes the objects to flow upward from a moving bed thereof to a disengaging position from where they fall onto an inclined distribution surface, are fed into an annular channel having at least an inclined section, and move downward through the inclined section to a feed position at the fluid inlet. The vessel may be used for treating electrically conductive objects wherein the fluid is an electrolyte, an electrode is positioned to contact the moving bed, and a counterelectrode is positioned in spaced relation to the vessel, which may be fixed or portable.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/068,498, filed Dec. 22, 1997, and is a Continuation-In-Part of U.S. application Ser. No. 10/176,260 filed Jun. 20, 2002, which was a Continuation of International Application No. PCT/US00/35413 filed Dec. 28, 2000, which was a Continuation-In-Part of U.S. application Ser. No. 09/216,859 filed Dec. 21, 1998, now U.S. Pat. No. 6,193,858 issued Feb. 27, 2001, the entire contents of this patent and these prior applications being expressly incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to the use of spouted beds of particles, pieces, parts and other small objects for the treatment thereof in a liquid or gaseous fluid. The invention has particular application for the electroplating of small parts which are difficult to plate by conventional means. The invention also has application in the fields of wastewater treatment, electrowinning, electrochemical synthesis, anodic electrochemical smoothing, anodizing, electrophoretic polymer coating, and physical coating, as well as in the general field of spouted bed applications.

BACKGROUND OF THE INVENTION

Barrel plating, in which objects are tumbled in a perforated horizontal rotating drum, is a common method of electroplating small parts. Representative technology is disclosed in U.S. Pat. No. 4,822,468 by Kanehiro and U.S. Pat. No. 4,769,117 by Shino, et al. Many very small parts cannot be plated effectively in a barrel due to poor contact with the current feeder or fouling on the interior of the drum. These problems often necessitate the addition of plating media (typically some type of smooth metal shot) to the barrel to improve cathodic contacting and part motion. The use of media significantly increases the required plating time and current because the media is also plated and, therefore, the plating cost per part is increased. Additionally, many small parts are fragile or can interlock and may be damaged by tumbling with heavy media. Consequently, these parts cannot be plated successfully in barrels.

U.S. Pat. No. 5,487,824 by Greigo discloses an integrated electroplating system designed specifically to electroplate very small parts which employs a horizontal accelerating rotating drum to maintain a packed bed of parts in motion during electroplating.

U.S. Pat. No. 3,1124,098 by Backhurst et al. and U.S. Pat. No. 3,703,446 by Haycock et al. disclose fluidized bed cathodes. Although fluidized beds have excellent liquid-solid contacting, fluidized bed cathodes suffer from poor electrical contact between the fluidized particles, non-homogeneous electrical potentials and particle segregation effects. Additionally, it is difficult to maintain the entire bed fluidized when the particles are changing in size, and possibly density, due to metal deposition. It is unlikely that the potential benefits of the fluidized bed approach will be realized in a practical electrodeposition system.

Typical spouted beds consist of a cylindrical vessel with a conical bottom section. The vessel contains a bed of particles which form the spouted bed. Fluid is introduced into the spouted bed vessel at the bottom of the conical section as a jet. This fluid jet penetrates the bed of particles contained in the spouted bed vessel, entraining particles and forming a “spout” of upward moving particles and fluid. The particles disengage from the fluid flow in a region above the particle bed and then fall on top of the downward-moving annular bed. The “pumping action” provided by the spout circulates the particles through the vessel in a torroidal fashion; upwards in the spout and downwards in the annular moving bed. A “draft pipe” may be incorporated into the vessel to assist in the fluid transport of the particles. The draft pipe consists of a tube which is fixed coincident with the location of the spout, directly above and aligned with the liquid jet. The draft pipe delays the dispersion of the liquid jet and allows particle transport over a broader range of fluid velocities while also stabilizing the liquid flow.

U.S. Pat. No 4,272,333 by Scott discloses the use of a moving bed electrode (MBE), in which conductive particles move downward vertically in a packed bed between two electrodes, the anode being shielded with a membrane. The necessity of using a membrane to shield the anode makes this configuration less attractive for practical applications, since the mechanical abrasion of the moving bed of particles can damage the membrane in a short time. Additionally, metal deposition on the membrane may be a complication.

An article by Hadzismajlovic et al. published in Hydrometallurgy, Vol. 22, pages 393-401 (1989), and U.S. Pat. No. 1,789,443 by Levin disclose the use of spouted bed cathodes with anodes suspended above the spouted bed surface. Although this configuration may eliminate the complication of shielding electrodes using membranes, several operational problems may be encountered with this configuration. Many electrolytes have poor electrical conductivity; therefore, it is advantageous to have the cathode and anode in close proximity in order to reduce the voltage drop over the cell. This cannot be accomplished in these prior art systems, since the spout would collide with the anode. Additionally, the projected spouted bed geometric surface area is very limited, impairing electrode performance.

Conventional spouted beds also suffer from a particle recirculation problem commonly referred to as “dead spots”, where a portion of the particle bed is stagnant. Dead spots usually exist at the outer edge of the spouted bed surface and are attributable to a failure of the spout to deposit particles at the circumference of the spouted bed. In an attempt to remedy this problem, spouted beds with very steep bottom cone angles have been adopted. In all cases, the radius of the spouted bed has been strictly limited to the distance to which particles in the spout can be transported radially outward by the fluid flow.

SUMMARY OF THE INVENTION

In the present invention, a distribution means has a solid body with a conical distribution surface extending from the vicinity of the upper edge of a draft pipe downward and radially outward towards the vessel sidewall to an annular channel for forming a downwardly moving annular packed bed, and is used to convey parts, pieces, particles or other small objects to this annular spouted bed by preventing the objects from falling near the center of the spouted bed vessel. Instead, the objects disengage from the spout and are deposited on the upper distribution surface of the distribution body. The objects then move along this surface until they are deposited in the annular channel at or beyond the outside edge of the distribution surface.

Use of the distribution body totally eliminates stagnant areas at the circumference of the spouted bed. Moreover, the distribution body allows very large diameter spouted beds to be constructed at modest fluid flow rates, since it is no longer necessary to transport objects to the spouted bed circumference dynamically via the fluid flow. The distribution body may comprise an upper shield member as shown in the related applications referred to above and a lower separate spacer member similar to that described below. However, an integral shield and spacer body with an upper distribution surface as specifically described below is preferred. Additionally, when such a distribution body or shield is used, large diameter shallow spouted beds with shallow bottom cone angles may be employed. In this type of bed, the motion of the objects is more radially inward rather than downward. Thus, the annular moving bed of the present invention is particularly advantageous for circulating fragile objects where the weight of a deep, small diameter bed may crush or break the objects, and is particularly useful for spouted beds of conductive or partially conductive parts serving as high performance electrodes where large projected areas and shallow bed depths are desirable.

A portable electroplating apparatus, which incorporates a pump and a vessel which defines a spouted bed electrolytic reaction chamber, is also provided by the present invention. The portable electroplating vessel can be conveyed from process tank to process tank by hand, automated plating system, or hoist. The spouted bed vessel is mounted on a platform with a pump to provide the necessary electrolyte flow for the spouted bed chamber. It is advantageous to incorporate a liquid by-pass circuit and adjustment valve so that the liquid flow to the spouted bed chamber can be adjusted. The liquid flow to the spouted bed chamber can also be adjusted by electronically controlling the speed of the pump. It is also desirable for the spouted bed vessel to be easily detachable from the portable apparatus and also for the internal components to be easily detachable from the vessel to facilitate access to the vessel interior.

In a further modification of the invention, each process tank may be equipped with a corresponding pump and control valve having a coupling or docking station to which the spouted bed vessel is easily attached and detached so that a spouted bed vessel without its own pump and valve may be conveyed between process tank docking stations.

In the practice of the present invention, conductive parts are electroplated while being circulated in a liquid spouted bed, in which the liquid is an electrolyte containing metal ions. The parts form an annular moving packed bed which is maintained under cathodic current by being in contact with a current feeder. The passage of current through the parts causes metal to be deposited from the electrolyte onto the parts as they circulate in the apparatus. Typically, the parts are retained in a non-conductive cylindrical vessel with a conical bottom section, although vessels with other geometries may also be used, provided they also have a downward inwardly inclined bottom section. The vessel may be made of a non-electrically conductive plastic material, for example polypropylene.

The electrolyte is introduced into the vessel as a jet at the bottom of a conical section into the bed of parts to be plated. The liquid jet entrains parts which disengage from the liquid flow in a region above the jet, then move radially outward to an annular channel, and then move downward and radially inward as an annular moving packed bed of parts. The action provided by the liquid jet thus circulates the parts through the vessel; first upwards and radially outward in the jet and then downward and radially inward in the packed bed. The cathodic connection is made with the packed bed via metallic contacts or a current feeder attached to the outside of the distribution body, or optionally inserted into the packed bed from above or attached to the inside wall of the vessel, to a side surface of a separate distribution shield member or to a side or lower surface of a separate spacer member below the distribution shield member.

If the surfaces of the parts to be plated are entirely conductive, the current feeder may be small in size with respect to the particle bed. If the parts are partially conductive by having non-conductive elements, as is the case with surface mounted electronic components, it is desirable to employ current feeders with a much larger surface area to insure that electrical contact is made with the conductive portions of the parts during their movement in the moving bed. For example, a majority of the vertical and inclined outer surfaces of the distribution body may be lined with a conductive material and used as a current feeder, or a large internal surface of the vessel below the distribution surface and in contact with the moving bed may be conductive and electrically connected as the cathodic current feeder. Large cathodic current feeders are preferred when plating partially conductive parts even when the parts are mixed with conductive media. Additionally, it is advantageous to use a mixture of conductive media and parts in the present invention when the parts are partially conductive. The counterelectrode (anode) maybe suspended above the moving packed bed in the spouted bed chamber, but preferable is located external to the vessel defining the spouted bed chamber.

The invention also may use a current feeder with a bumpy or otherwise textured surface to facilitate movement of the objects and to prevent the objects from sticking to the current feeder during electrodeposition. Bumps about the size of the objects are particularly useful for preventing rectangularly shaped objects from jamming together and “tiling” as they slide over the current feeder. Moreover, a bumpy or otherwise textured current feeder surface reduces the contact area between the objects and the current feeder, thereby decreasing the possibility that the objects will become fused to the current feeder during electroplating.

A “draft pipe” is incorporated into the distribution body to assist in the hydraulic transport of the parts. The draft pipe comprises a passage or conduit in the distribution body that may be cylindrical or have some other shape, and the entrance to which is fixed coincident with the location of the spout, namely, directly above and aligned with the liquid jet. The draft conduit delays dispersion of the liquid jet and allows part transport over a broader range of liquid velocities.

Additionally, it is preferable to employ a parts deflector located above the draft conduit. The parts deflector is a conical point or a flat disk or a downwardly facing concave surface, which is located above the spout. The deflector prevents the parts in the spout from exiting the chamber by directing the part trajectories toward the sidewall of the vessel. It also prevents the jet of entrained parts from colliding with any overhead components in the chamber. The parts deflector is particularly advantageous in conjunction with the draft conduit, since the presence of the draft conduit strengthens the flow of the spout.

It is also preferred to employ a distribution surface. The distribution surface may be conical and extend from the vicinity of the upper edge of the draft conduit to an annular space or channel between a wall of the vessel and an opposing surface of the internal spacer member. This surface aids in distributing the parts to the annular spouted bed by preventing parts from falling near the center of the reaction chamber. Instead, these parts move along the distribution surface until they are deposited at the top of the annular moving bed of parts.

In the present invention, one or more counter electrodes may be used and they are typically anodes. The counter electrodes are preferably located external to the spouted bed vessel, which is at least partially immersed in the electrolyte, and in close proximity to the exterior of the vessel sidewall(s). Openings are provided in the immersed portion of the sidewall(s) and/or bottom wall(s) of the spouted bed vessel to allow the passage of current via the electrolyte from the external counter electrodes to the moving packed bed of objects contained in the spouted bed vessel. The submerged vessel openings may be covered by a fine screen, a mesh, cloth or membrane which allows the passage of electrical current and prevents the loss of the objects from the spouted bed vessel. These openings may also serve as means for the electrolyte to exit the spouted bed vessel.

Typically, external soluble anodes comprised of the same metal as is dissolved in the electrolyte are desirable in electroplating applications where the spouted bed vessel may be conveyed between a plurality of processing tanks. Although insoluble anodes may also be used for these and other applications of the present invention, they are typically used for precious metal plating.

The liquid electrolyte is injected into the reaction chamber via a pump and, during operation, this arrangement presents no difficulties. However, when operation of the device is interrupted, the parts from the bed may fall into the outlet of the pump via gravity, effectively fouling the pump. Therefore, a means of retaining the parts in the vessel is provided. One approach is to incorporate a screen at the jet inlet which will not allow the parts to pass. If a screen is used, it is preferable to filter the fluid upstream of the screen to prevent fouling.

An alternate approach is to utilize a solid “trap” arrangement. This can be a simple “U” pipe on the inlet line, or can consist of two concentric pipes which cause the liquid to reverse direction. In either case, the parts are trapped due to their density difference with respect to the electrolyte. An access port can be incorporated into the trap to allow the parts to be conveniently removed from the spouted bed chamber. Alternately, a gate or slide valve may be used to seal the inlet pipe when the flow is interrupted.

The present invention may also be practiced using rectangular vessels with inward downwardly inclined (slanted) bottoms. In this case, the distribution shield would be an angled flat plate or plates, and the draft conduit and inlet pipe may be either tubular or rectangular. The present invention also contemplates that the spouted bed vessel may be used in a stationary configuration in which the various cleaning, plating and rinse solutions are sequentially introduced from separate holding tanks, circulated through the reaction chamber for the appropriate time, and then purged from the spouted bed vessel via a manifold piping system connected to solution reservoirs, control valves, control system and pumps.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its assembly and operation may be further understood from the following description of the preferred embodiments thereof, which are shown by way of example in the accompanying drawings wherein:

FIG. 1 is a cross-sectional elevational view of a portable spouted bed electrochemical reactor vessel and a stationary electrolyte tank and docking system made in accordance with the present invention;

FIG. 2 is an exterior top view of a spouted bed plating apparatus as modified to provide a self contained portable unit in accordance with the invention; and,

FIG. 3 is a cross-sectional elevational view of the apparatus of FIG. 2 as taken along line 3-3 of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now in greater detail to the appended drawings, FIG. 1 shows a detailed cross-sectional view of a portable spouted bed reaction chamber or reactor 1, removeably situated in a stationary process tank 40. The stationary process tank 40 is equipped with a pumping system to supply a liquid stream of electrolyte to spouted bed chamber 1, and is further equipped with stationary electrodes 8, which are external to the chamber 1 and function as counter electrodes to the objects 3 contained in chamber 1. When electroplating objects 3, electrodes 8 function as anodes. Tank 40 may be one of a series of process tanks between which portable spouted bed chamber 1 is conveyed during an electroplating process that will circulate through chamber 1 successive processing solutions, such as cleaning, plating and rinsing solutions. As an alternative, chamber 1 may be fixed to tank 40 and successive processing solutions passed through tank 40 from a plurality of process tanks.

The spouted bed chamber 1 consists of a cylindrical vessel 2 with a conical bottom 11 and a detachable top or cover 12. Vessel 2 is made of a material, such as polyethylene, that is not electrically conductive. The vessel 2 of spouted bed chamber 1 is partially immersed in the liquid electrolyte L contained in tank 40, as is indicated by liquid surface S. The electrolyte is injected into the chamber 1 by an external pump 34 via a ball flow regulating valve 32, a socketed fitting 30 and an inlet pipe 18 having an attached mesh screen 17. Pump 34 is connected in a closed loop that is completed by tank 40, a tank outlet fitting 38, a liquid strainer 36 and associated plumbing.

The portable spouted bed chamber 1 may be detachably connected to tank 40 by inserting inlet pipe 18 into socketed coupling 30 as shown in FIG. 1. The inlet pipe is connected to the spouted bed vessel 2 via a socketed receptacle 19. Pin 15 is used to retain inlet pipe 18 in socketed receptacle 19. Mesh screen 17 is attached to the end of inlet pipe 18 and retains the treated objects in the vessel 2 when the liquid flow through the vessel is discontinued. Pin 15 and inlet pipe 18 and attached mesh 17 can be easily removed to allow the unloading of objects from the bottom of vessel 2 of the spouted bed chamber 1.

Liquid enters vessel 2 via the inlet pipe 18 and forms a jet that entrains small parts or other objects and carries them into and through a passage or conduit 4 passing axially through an internal spacer member 9 having an upper portion which forms a shield with a conical distribution surface 20. Although the spacer member and the distribution shield may be separate components, they are preferably made as a single integral piece as shown in FIG. 1. The liquid jet with entrained objects moves through conduit 4 and impinges on a deflector 6 that is suspended from the vessel cover 12 and preferably has a downwardly facing concave surface. Deflector 6 directs the entrained objects radially outward and downward, thereby disengaging the objects from the liquid jet.

The disengaged objects are deposited on the upper distribution surface 20 of spacer member 9 where they move radially outward and downward until they slide off surface 20 and are deposited in a confining channel 3 that is preferably annular and is formed by opposing surfaces of spacer member 9 and the sidewall of vessel 2. Both of the opposing surfaces forming annular channel 3 preferably have vertically oriented portions and inward downwardly inclined portions, and the objects deposited in the annulus therebetween form an annular moving bed. However, the opposing surfaces of channel 3 may optionally have only inward downwardly inclined portions resembling a pair of concentric funnels, with the outer funnel being both the side wall and bottom wall of a vessel without a vertical wall portion or having a vertical wall portion at or above the annulus. Also, channel 3 may be only partially annular, such as being an arcuate channel or a channel divided into two or more arcuate segments each of which forms a correspondingly arcuate segment of the downwardly moving bed of small parts.

The confined bed of the objects moves vertically downward and then radially inward and downward in a moving packed bed towards the gap between the upper end of inlet pipe 18 and the lower entrance end of conduit 4. The inclined portions of the opposing surfaces, and the conical distribution surface 20, are inclined at an angle in the range of preferably about 20° to about 80°, more preferably about 30° to about 50°, from the horizontal.

Spacer member 9 is attached to the cover 12 of vessel 2 by one or more vertical supports 22. The cover 12, supports 22, spacer member 9 and deflector 6 form a detachable assembly which is readily removed by lifting the chamber cover 12 from the spouted bed vessel 2, thus providing easy internal access to vessel 2.

Electrical contact with the annular moving bed of objects is made by an arcuate or annular current feeder 16 that is electrically conductive and is attached to spacer member 9, preferably so as to form at least a portion of its circumference. Current feeder 16 is connected to an external electrical power supply by a cathodic connection comprising an electrically conductive rod 10 that preferably runs axially through one or more of the supports 22 and is connected to a cathodic connector 23. The outer surface of current feeder 16 may have bumps, or be roughened or otherwise textured to facilitate movement of the objects thereover.

In the embodiments shown in the drawings for coating small objects with a metal constituent of the electrolyte, the electrodes in contact with the moving bed of objects are connected to the negative terminal of the power source and function as cathodes, and the counter-electrodes 8 are mounted in the stationary tank 40 in proximity to vessel 2 and are connected to the positive terminal of the power source and function as anodes. Current is conducted from the anodes to the moving objects via one or more openings 25, 26 and 27 in the sidewall of vessel 2 and in the bottom wall 11, these openings being covered by a porous screen, mesh, cloth, membrane or other porous medium for retaining the objects within the vessel while passing current. Liquid pumped into the vessel 2 via inlet pipe 18 exits the vessel primarily via the covered openings 27 that are above the level of the bed 3.

In implementing the embodiment of FIG. 1, as well as the embodiments of FIGS. 2-3, a pumping means and a docking means may be provided for each of a series of process tanks. An automated means for detecting the presence of a reactor vessel in each process tank may also be provided and used to automatically switch on the pump serving the tank. The detection means may be a physical contact switch (not shown) in the tank, or a magnetic hall effect sensor 72 on the outside of the tank and a magnet 73 attached to the inlet pipe 18 of the reactor vessel 2 as shown in FIG. 1. The detection means may also include a relay module 74 responsive to inputs from sensor 72 to control an A.C. power supply 76 for operating the pump 34.

In the embodiment of FIGS. 2 and 3, a sensor like the sensor 72 may be located under the lip 71 in the vicinity of the position for a rail 70 and a magnet like the magnet 73 may be attached to the corresponding rail. For such a physical or magnetic detection means, there may be substituted an optical detector, or any other means which can be effectively implemented to serve this purpose. Thus, it is an object of the present invention that the pump for each tank used with the embodiments of FIGS. 1-3 may be automatically activated when a reactor vessel is present and deactivated when the vessel is removed.

FIG. 2 shows a top view of a portable plating apparatus 41 having a spouted bed reactor vessel 50 removably situated in a process tank 87 containing a process solution L with its surface designated by S. The internal components of vessel 50 are preferably the same as those shown for vessel 2 in FIG. 1. This apparatus may be used in an analogous manner to a plating barrel or plating rack in that it is designed to be conveyed from tank to tank for circulating through vessel 50 successive processing solutions, such as cleaning, rinsing, and plating solutions.

FIG. 3 shows a sectional view of apparatus 41 taken along line 3-3 of FIG. 2. The lower portion of the apparatus is immersed below the surface S of the process solution L, and the entire apparatus is supported by side rails 70, 70, which rest on a sidewall lip 71 of each process tank 87 and are equipped with handles 86, 86. The apparatus includes transverse platforms 52 and 54, which connect the side rails 70, 70. A submersible head centrifugal pump 88 is mounted on platform 54. The inlet of the pump is attached via an elbow 94 to a liquid strainer 95. The outlet 96 of the pump is connected via a short segment of plastic pipe to a plastic T fitting 97.

The inlet pipe 98 of the spouted bed vessel 50 is detachably coupled to the T fitting 97. The third opening of the T fitting 97 is attached via a plastic pipe and elbow 99 and a plastic pipe 60 to a bypass ball valve 90. The outlet of ball valve 90 returns solution to the process tank 87 via the segments of plastic pipe and elbows shown in FIGS. 2 and 3. The amount of solution circulated through the spouted bed vessel 50 can be adjusted by using the bypass valve 90. The liquid flow to the spouted bed chamber can also be adjusted by electronically controlling the speed of the pump. The spouted bed vessel 50 is open to the atmosphere and has a plurality of mesh covered openings 55 and 56 in the vessel sidewall and a plurality of mesh covered openings 57 in the vessel bottom wall. Solution is returned to the process tank via these mesh covered openings, primarily the openings 55 that are above the level of the annular bed.

The negative direct current electrical connection (cathode) to the circulated objects in vessel 50 is via an electrical connector 48 passing through cover 12′ of vessel 50. The counter electrodes or anodes 44 are suspended in the process tank 87 in proximity to the vessel 50 by conductive connectors 43 carried by conductive support rods 42, which are connected to the positive terminal of a direct current power supply. Current passes between anodes 44 and the circulated objects contained in vessel 50 primarily via openings 56 and 57 in vessel 50.

Persons skilled in the art, upon learning of the present disclosure, will recognize that various modifications to the components and elements of the invention are possible without significantly affecting their functions. For example, the specific vessel structure described above may be varied widely in accordance with spouted bed technology, and may have shapes other than cylindrical, such as four sidewalls defining a rectangular chamber and either a single rectangular bottom wall inclined downwardly to the vessel inlet or opposing rectangular bottom walls converging downwardly toward the vessel inlet. Also, the confining channel 3 at the edge of the distribution surface may have shapes other than circular, such as rectangular, pentagonal, hexangular or octagonal.

Similarly, the positions of the anode and cathode may be reversed so that metal objects may be polished by having an outer layer removed electrolytically. Furthermore, the apparatus disclosed may be used with a gaseous fluid in combination with a chemical coating composition in order to coat recirculating objects with the chemical composition instead of a metal, thereby providing a spouted bed coating apparatus of the type represented in general by that disclosed in U.S. Pat. No. 5,254,168 issued Oct. 19, 1993, to Littman, et al., the entire contents of this patent being incorporated herein by reference. Accordingly, while the preferred embodiments have been shown and described in detail by way of example, further modifications and embodiments are possible without departing from the scope of the invention as defined by the claims set forth below. 

1. An apparatus for electrolytically treating a plurality of at least partially electrically conductive objects with an electrolytic fluid to transfer a constituent of the fluid between the fluid and the objects, said apparatus comprising: a vessel having an inclined wall inclined downwardly toward a fluid inlet arranged to provide an upwardly directed stream of said fluid for causing said objects to flow upward from a feed position adjacent to said inlet to a disengaging position at which said objects are disengaged from said stream; a distribution means mounted in said vessel and having a distribution surface inclined downwardly and extending away from the vicinity of said disengaging position to a return position such that said disengaged objects fall on said distribution surface and move downwardly thereon away from said disengaging position to said return position, said return position being arranged to deposit said disengaged objects into a channel for conveying said disengaged objects to said feed position, said channel having at least an inclined portion defined by said inclined wall and an opposing inclined surface of a channeling portion of said distribution means, and said channeling portion being arranged to cause a bed of said deposited objects to move downward along said inclined wall while in contact with said opposing inclined surface; a conduit mounted in said vessel and arranged above said fluid inlet for receiving said upward flow of objects, said conduit extending upwardly to confine the flow of said objects from the vicinity of said feed position to the vicinity of said disengaging position; and, an electrode positioned to contact said moving bed and a counterelectrode positioned in spaced relation to said moving bed and arranged to contact said fluid, said vessel being at least partially immersed in said fluid, said counterelectrode being located outside of and in proximity to an immersed portion of said vessel, and said inclined wall or a side wall of said vessel having at least one opening immersed in said fluid to allow a current flow between said objects and said counterelectrode.
 2. An apparatus according to claim 1, wherein said channel further comprises an arcuate portion extending vertically from said inclined portion and having in inlet arranged adjacent to said return position for receiving said deposited objects, said arcuate portion being defined by a surface of a side wall of said vessel and an opposing vertically extending surface of the channeling portion of said distribution means, and said arcuate channel portion being arranged to form an arcuate bed of said deposited objects and cause said arcuate bed to move downward toward said inclined wall while in contact with said opposing vertically extending surface.
 3. An apparatus according to claim 2, wherein said electrode comprises an electrically conductive member mounted on said distribution means and arranged to contact said moving bed of objects in said arcuate channel portion.
 4. An apparatus according to claim 3, wherein said electrically conductive member has an arcuate shape and extends at least partially around a body member of said distribution means.
 5. An apparatus according to claim 1, wherein said channel has an annular cross section and extends around a body member of said distribution means to cause formation of an annular bed of said deposited objects.
 6. An apparatus according to claim 1, wherein said inclined wall and said opposing surface each have a conical shape.
 7. An apparatus according to claim 1, wherein said conduit confines the flow of said objects from the vicinity of said feed position to at least the vicinity of said distribution surface and is arranged to cause said upward flow of objects to pass through an opening in said distribution surface, and wherein a central portion of said distribution surface is continuous with an upper portion of a wall of said conduit.
 8. An apparatus according to claim 1, wherein said electrode comprises an electrically conductive member mounted on said distribution means and arranged to contact said moving bed of objects.
 9. An apparatus according to claim 8, wherein said electrically conductive member has an arcuate shape and extends around at least part of a periphery of a body member of said distribution means.
 10. An apparatus according to claim 1, wherein said opening is covered with a porous medium to retain said objects within the vessel.
 11. An apparatus according to claim 1, wherein said distribution means and said electrode are detachably suspended in said vessel and are removable to permit internal access to the said vessel.
 12. An apparatus according to claim 1 further comprising means for detachably mounting said vessel on a container for holding a body of fluid in which said vessel is at least partially immersed.
 13. An apparatus according to claim 12, wherein said container includes fluid outlet means for discharging said fluid from said container; and wherein said apparatus further comprises means for supplying to said vessel inlet a supply of said fluid from a corresponding source, and means for returning said fluid from said outlet means to said corresponding source from which the fluid was supplied.
 14. An apparatus according to claim 13, wherein said supply means comprises pump means for conveying fluid to said vessel inlet from the container on which said vessel is mounted; valve means for controlling the flow of fluid from said container to said vessel inlet; and a frame for supporting said vessel, said pump means and said valve means as a portable unit for transfer between a plurality of said containers.
 15. An apparatus according to claim 14 further comprising detection means for detecting the presence of said vessel in each of said containers, and switch means responsive to said detection means for automatically operating said pump means when said vessel is present in a corresponding one of said containers.
 16. An apparatus according to claim 12, wherein said vessel is a portable structure comprising a fitting for connecting said inlet to a supply conduit for supplying said fluid to said vessel.
 17. An apparatus according to claim 16 further comprising a bypass conduit connected to said supply conduit for recycling at least a portion of the fluid in said container, and a control valve for controlling fluid flow in said bypass conduit so as to regulate the amount of fluid flow reaching said vessel inlet.
 18. An apparatus according to claim 1 further comprising a deflecting member mounted above said distribution means and located in the vicinity of said disengaging position so as to intercept said upwardly flowing objects and deflect them away from said fluid stream.
 19. An apparatus according to claim 18, wherein said deflecting member has a concave surface for intercepting and deflecting the objects.
 20. An apparatus according to claim 1, wherein said bottom wall and said distribution surface are each inclined at an angle in the range of about 20° to about 80° from the horizontal.
 21. An apparatus according to claim 1, wherein said fluid in said vessel is a mixture of a liquid and a gas, and wherein said distribution means comprises a spacer body under said distribution surface to prevent an accumulation of gas under said distribution surface by filling a space beneath said distribution surface.
 22. An apparatus for electrolytically treating a plurality of objects with an electrolytic fluid while immersed in said fluid, said objects being at least partially electrically conductive and said apparatus comprising: a vessel having an inclined wall inclined downwardly toward a fluid inlet arranged to provide an upwardly directed stream of said fluid for causing said objects to flow upward from a feed position adjacent to said inlet to a disengaging position at which said objects are disengaged from said stream; a distribution means mounted in said vessel and having a distribution surface inclined downwardly and extending away from the vicinity of said disengaging position to a return position such that said disengaged objects fall on said distribution surface and move downwardly thereon away from said disengaging position to said return position, said return position being arranged to deposit said disengaged objects into a channel for conveying said disengaged objects to said feed position, said channel having at least an inclined portion defined by said inclined wall and an opposing inclined surface of a channeling portion of said distribution means, and said channeling portion being arranged to cause a bed of said deposited objects to move downward along said inclined wall while in contact with said opposing inclined surface; and, an electrode positioned to contact said moving bed and a counterelectrode positioned to contact said fluid, said vessel being at least partially immersed in said fluid, said counterelectrode being located outside of and in proximity to an immersed portion of said vessel, and said inclined wall or a side wall of said vessel having at least one opening immersed in said fluid to allow a current flow between said objects and said counterelectrode.
 23. An apparatus according to claim 22 further comprising: pump means for conveying said fluid from a container to said vessel inlet; control valve means for controlling the flow of fluid from said container to said vessel inlet; and, a frame for engaging said container and supporting thereon said vessel, said pump means and said valve means to provide a portable unit for transfer between a plurality of containers.
 24. An apparatus according to claim 22, wherein said distribution means further comprises a conduit arranged above said fluid inlet for receiving said flow of objects, said conduit extending upwardly to confine the flow of said objects from the vicinity of said feed position to at least the vicinity of said distribution surface and being arranged to cause said upward flow of objects to pass through an opening in said distribution surface.
 25. An apparatus according to claim 22, wherein said channel further comprises an arcuate portion extending vertically from said inclined portion and having in inlet arranged adjacent to said return position for receiving said deposited objects, said arcuate portion being defined by a surface of a side wall of said vessel and an opposing vertically extending surface of the channeling portion of said distribution means, and said arcuate channel portion being arranged to form an arcuate bed of said deposited objects and cause said arcuate bed to move downward toward said inclined wall while in contact with said opposing vertically extending surface.
 26. An apparatus according to claim 25, wherein said electrode comprises an electrically conductive member mounted on said distribution means and arranged to contact said moving bed of objects in said arcuate channel portion, and wherein said electrically conductive member has an arcuate shape extending at least partially around a periphery of a body member of said distribution means.
 27. An apparatus according to claim 22, wherein said channel has an annular cross section and extends around a body member of said distribution means to cause formation of an annular bed of said deposited objects.
 28. An apparatus according to claim 22 further comprising a deflecting member mounted above said distribution surface and located in the vicinity of said disengaging position so as to intercept said upwardly flowing objects and deflect them away from said fluid stream.
 29. An apparatus according to claim 22, wherein said opening is covered with a porous medium to retain said objects within the vessel.
 30. An apparatus for contacting a plurality of objects with a fluid, said apparatus comprising: a vessel having an inclined wall inclined downwardly toward a fluid inlet arranged to provide an upwardly directed stream of said fluid for causing said objects to flow upward from a feed position adjacent to said inlet to a disengaging position at which said objects are disengaged from said stream; a distribution means mounted in said vessel and having a distribution surface inclined downwardly and extending away from the vicinity of said disengaging position to a return position such that said disengaged objects fall on said distribution surface and move downwardly thereon away from said disengaging position to said return position, said return position being arranged to deposit said disengaged objects into a channel for conveying said disengaged objects to said feed position, said channel having at least an inclined portion defined by said inclined wall and an opposing inclined surface of a channeling portion of said distribution means, and said channeling portion being arranged to cause a bed of said deposited objects to move downward along said inclined wall while in contact with said opposing inclined surface; and, an electrode arranged to contact said moving bed and a counterelectrode arranged to contact said fluid, said fluid being a liquid electrolyte comprising a metal for coating said objects and said objects being at least partially electrically conductive, said vessel being at least partially immersed in said fluid, said counterelectrode being located outside of and in proximity to an immersed portion of said vessel, and said inclined wall or a side wall of said vessel having at least one opening immersed in said fluid to allow current to flow between said objects and said counterelectrode.
 31. An apparatus according to claim 30, wherein said channel further comprises an annular portion extending vertically from said inclined portion and having in inlet arranged adjacent to said return position for receiving said deposited objects, said annular portion being defined by a surface of a side wall of said vessel and an opposing vertically extending surface of the channeling portion of said distribution means, and said annular channel portion being arranged to form an annular bed of said deposited objects and cause said annular bed to move downward toward said inclined wall while in contact with said opposing vertically extending surface.
 32. An apparatus according to claim 31, wherein said electrode comprises an electrically conductive member mounted on said distribution means and arranged to contact said moving bed of objects in said annular channel portion, and wherein said electrically conductive member has an annular shape extending around a periphery of a body member of said distribution means.
 33. An apparatus according to claim 30 further comprising a deflecting member located in the vicinity of said disengaging position for intercepting and disengaging said upwardly flowing objects from said fluid stream.
 34. An apparatus according to claim 30, wherein said distribution means further comprises a conduit arranged above said fluid inlet for receiving said flow of objects, said conduit extending upwardly to confine the flow of said objects from the vicinity of said feed position to at least the vicinity of said distribution surface and being arranged to cause said upward flow of objects to pass through an opening in said distribution surface.
 35. An apparatus according to claim 30, wherein said channel has an annular cross section and extends around a body member of said distribution means to cause formation of an annular bed of said deposited objects. 